STS 30 break in temps

[locky]

So I went for the STS 30 rotostart after looking at SH/STS engines

 

Installed it in my Savage 25 but found that I could not get the rotostart shaft engaged, as the STS rotostart slot is lower than HPI's, So fitted into my Savage X, but still not perfect as wheelie bar is in way and have to go in at an angle with the shaft.

 

Also had to file pipe header on bottom 2 corners to get it past rotostart backplate onto exhaust gasket.

 

I resealed the backplate and carb before installing and checked needles were at factory settings.

 

Loosened glow plug and starts and idles rich with idle rpm slightly raised on transmitter.

 

The temps rise quickly to 250 F, so I then shut it down and let it cool with piston at BDC.

 

Repeated this 8 times, letting idle for few minutes til temps reach 250 F.

 

Pinch test - dies at 2 secs, no rpm increase,

 

Richened LSN up to 1 turn but still dies at 2 secs.

 

Just got feeling that something not right.

 

Recently broke in LRP 28 Spec 3 and temps stay at about 220 F.

 

Was thinking of trying carb from K4.6 to see if made any difference, but saw that the o-ring is on the STS engine and not the STS carb body, so unsure if the HPI carb will fit.

 

 

[jordan_bench10]

Hpi carb will not fit chap

Sts only i believe however these temps arentreally all that far away from what i remember right when i broke my sts in its ecause its so tight when new these temps should drop over a few tanks 10 max as it will start loosening up nicely then

Also what fuel are you using ? I was using 25% and can remember seeing upto 270f

[atom3624]

My ZR32 LRP used to get me worried, going up to 290. 220-250 Fahrenheit should be fine I reckon.

I wouldn't let it go higher, until it's properly bedded in, showing signs of loosening up a bit.

 

Al.

[locky]

I removed the HSN, cleaned and greased and set to 3 turns out. It now sits just below top of needle.

 

I unscewed the LSN  but could not completely remove it, I did not want to use excessive force and tear the o-ring, so removed the throttle slide, cleaned and greased. When I reinstalled the throttle slide and reset the LSN and idle, I could see that the LSN was now proud and not flush when at 4.5 turns out.

 

It's running better and temps are lower, 220-250, while running at low throttle with blips and coasting. 

 

Pinch test is about 5 secs.

 

Can only think that there was something wrong with original needle set up or dirt on needles.

 

Just got fresh gallon of 25% to slowly break it in.

 

Is there any need to remove any shims after break in?

[locky]

There are 2 shims installed and one supplied, one 0.3 silver and one 0.2 copper/brass, so 0.5 for break in.

 

I was starting to get occasional backfires so replaced 0.2 shim with 0.1 copper/brass shim, giving 0.4, which is recommended by STS for 25%.

 

Backfires havent occurred since.

 

However the acceleration from low to mid rpms still seemed weak, even when leaned it out. Top end is OK.

 

I replaced the STS carb with the HPI K4.6 carb and now the acceleration is better, so will have to carefully inspect the STS carb.

[locky]

About gallon used so far with STS 30 and conclude that the HPI K4.6 carb makes it accelerate smoothly compared to STS carb and easier to tune. Swapped them several times and the acceleration is poor and rough with the STS carb, Maybe I got a duff carb.

 

From my recent experience the STS 30 is not as powerfull as LRP 28 spec 3, but it is a reasonable budget basher.

[atom3624]

It could just be the carb alignment?

Is the action nice and smooth?

 

Al.